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authorJan Beulich <jbeulich@novell.com>2008-12-16 11:28:14 +0000
committerSam Ravnborg <sam@ravnborg.org>2008-12-19 22:41:15 +0100
commitad7a953c522ceb496611d127e51e278bfe0ff483 (patch)
treef51a18ab282bb77244fc02ad33359a92b6b36eb9 /scripts/Makefile.build
parent37a8d9f67f18de1e2cbc7387311ce22d4dbff518 (diff)
downloadlinux-stericsson-ad7a953c522ceb496611d127e51e278bfe0ff483.tar.gz
kbuild: strip generated symbols from *.ko
This patch changes the way __crc_ symbols are being resolved from using ld to do so to using the assembler, thus allowing these symbols to be marked local (the linker creates then as global ones) and hence allow stripping (for modules) or ignoring (for vmlinux) them. While at this, also strip other generated symbols during module installation. One potentially debatable point is the handling of the flags passeed to gcc when translating the intermediate assembly file into an object: passing $(c_flags) unchanged doesn't work as gcc passes --gdwarf2 to gas whenever is sees any -g* option, even for -g0, and despite the fact that the compiler would have already produced all necessary debug info in the C->assembly translation phase. I took the approach of just filtering out all -g* options, but an alternative to such negative filtering might be to have a positive filter which might, in the ideal case allow just all the -Wa,* options to pass through. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build55
1 files changed, 35 insertions, 20 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index c1da14b9f59d..6a2153891592 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -151,16 +151,16 @@ cmd_cc_i_c = $(CPP) $(c_flags) -o $@ $<
$(obj)/%.i: $(src)/%.c FORCE
$(call if_changed_dep,cc_i_c)
-cmd_gensymtypes = \
+cmd_genksyms = \
$(CPP) -D__GENKSYMS__ $(c_flags) $< | \
- $(GENKSYMS) -T $@ -a $(ARCH) \
+ $(GENKSYMS) -T $@ -A -a $(ARCH) \
$(if $(KBUILD_PRESERVE),-p) \
$(if $(1),-r $(firstword $(wildcard $(@:.symtypes=.symref) /dev/null)))
quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
cmd_cc_symtypes_c = \
set -e; \
- $(call cmd_gensymtypes, true) >/dev/null; \
+ $(call cmd_genksyms, true) >/dev/null; \
test -s $@ || rm -f $@
$(obj)/%.symtypes : $(src)/%.c FORCE
@@ -177,28 +177,38 @@ cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
else
# When module versioning is enabled the following steps are executed:
-# o compile a .tmp_<file>.o from <file>.c
-# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
-# not export symbols, we just rename .tmp_<file>.o to <file>.o and
+# o compile a .tmp_<file>.s from <file>.c
+# o if .tmp_<file>.s doesn't contain a __ksymtab version, i.e. does
+# not export symbols, we just assemble .tmp_<file>.s to <file>.o and
# are done.
# o otherwise, we calculate symbol versions using the good old
# genksyms on the preprocessed source and postprocess them in a way
-# that they are usable as a linker script
-# o generate <file>.o from .tmp_<file>.o using the linker to
-# replace the unresolved symbols __crc_exported_symbol with
-# the actual value of the checksum generated by genksyms
+# that they are usable as assembly source
+# o assemble <file>.o from .tmp_<file>.s forcing inclusion of directives
+# defining the actual values of __crc_*, followed by objcopy-ing them
+# to force these symbols to be local to permit stripping them later.
+s_file = $(@D)/.tmp_$(@F:.o=.s)
+v_file = $(@D)/.tmp_$(@F:.o=.v)
+tmp_o_file = $(@D)/.tmp_$(@F)
+no_g_c_flags = $(filter-out -g%,$(c_flags))
+
+cmd_cc_o_c = $(CC) $(c_flags) -S -o $(s_file) $<
-cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
cmd_modversions = \
- if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
- $(call cmd_gensymtypes, $(KBUILD_SYMTYPES)) \
- > $(@D)/.tmp_$(@F:.o=.ver); \
- \
- $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
- -T $(@D)/.tmp_$(@F:.o=.ver); \
- rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
+ if grep -q __ksymtab $(s_file); then \
+ if $(call cmd_genksyms, $(KBUILD_SYMTYPES)) > $(v_file) \
+ && $(CC) $(no_g_c_flags) -c -Wa,$(v_file) \
+ -o $(tmp_o_file) $(s_file) \
+ && $(OBJCOPY) -L '__crc_*' -L '___crc_*' -w \
+ $(tmp_o_file) $@; \
+ then \
+ : ; \
+ else \
+ rm -f $@; exit 1; \
+ fi; \
else \
- mv -f $(@D)/.tmp_$(@F) $@; \
+ rm -f $(v_file); \
+ $(CC) $(no_g_c_flags) -c -o $@ $(s_file); \
fi;
endif
@@ -221,7 +231,12 @@ define rule_cc_o_c
$(cmd_record_mcount) \
scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' > \
$(dot-target).tmp; \
- rm -f $(depfile); \
+ if [ -r $(@D)/.tmp_$(@F:.o=.v) ]; then \
+ echo >> $(dot-target).tmp; \
+ echo '$@: $(GENKSYMS)' >> $(dot-target).tmp; \
+ echo '$(GENKSYMS):: ;' >> $(dot-target).tmp; \
+ fi; \
+ rm -f $(depfile) $(@D)/.tmp_$(@F:.o=.?); \
mv -f $(dot-target).tmp $(dot-target).cmd
endef